SDN itself offers questions given by interview panels. For me I used them and practiced with my wife. Just remember not to over practice, because then it won't appear to be from the heart. However, you still want to act like you at least thought about the question sometime before he asked you. I never used any thing else. One big tip to remember though.....don't think you have to answer every question. If you can't answer, then tell them you can't answer it. If you can reason it, then try for it. Don't put yourself into a hole you can't get out of.